Re: [ATM] [atm_free] Rush into F3.5

[Ukyo Chen <ukyochen888@hotmail.com>]

Dear Shane,
Thanks for the recommendation. The 645 euro corrector need a larger diagonal mirror than visual usage.
I would like to enjoy both visual & photograph, thus I can make 2 sets of wynne correctors, 1 have enough length to eyepiece and the other is small and short for a low centre obstruction.
 
Like what you care, the collimation may be difficult when switching between 2 sets diagonal&correctors.
Best Regards,
Ukyo Chen



> Date: Wed, 15 Nov 2006 09:10:47 -0500> To: ukyochen888@hotmail.com> From: shane@dreamscopes.com> Subject: Re: [ATM] [atm_free] Rush into F3.5> CC: atm@atmlist.net> > Ukyo,> > If you do not want to be forced to produce a hyperbola, there is a 0.73x > coma corrector/reducer that is 2" in diameter. It is made for parabolas as > fast as f3.0. You can see the technical information about this corrector > below:> http://www.astrooptik.com/sonstiges/NewtRedNew/ReducerNew.htm> > Do NOT contact Philipp Keller for additional information. Contact Egon > Doberl from ASA at the below e-mail address for questions and/or ordering:> egond@gmx.at> > If you are using a small CCD chip, smaller than 12mm square, switching > between the two systems you outline will be less stringent than if you plan > to use a 25mm x 36mm chip. Either way though it is not a trivial task > aligning such fast systems with a diagonal in the mix.> > If you want the most visually, you should use a coma corrector. TeleVue > sells a very nice visual corrector for this purpose, the Paracorr.> > The above correctors would give you the best performance for each emphasis > but they come at a price. Everything does...> > You might start with a question for yourself. Which do you plan to use it > for more: visual or imaging.> > If imaging is more important, then I would suggest you optimize the system > for the 0.73x reducer/corrector and imaging. Then use the system with this > secondary visually to see if the views meet your requirements. Again, if > you want the most visually, use a coma corrector visually as well. Not > having to change out the secondary and leaving the system fully collimated > will make life SO much easier for you.> > Thank you.> > Sincerely,> Shane Santi - President> Dream - Telescopes & Accessories, Inc.> http://www.dreamscopes.com> 610 - 365 - 2833> > > > At 04:02 AM 11/15/2006, you wrote:> >Or maybe I can make 2 sets of diagonal for a hyperbolic mirror+corrector, > >1 set with minimize size for visual (10% obstruction), another set for > >photograph (18.3% obstruction), and the system is F2.8 if the mirror is F3.5.> >> >The most difficult thing is figuring a hyperbolic mirror...> >> >Best Regards,> >Ukyo Chen
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